ABSTRACT
The neutron capture cross section of [Formula: see text]Ta is relevant to s-process of nuclear astrophysics, extraterrestrial samples analysis in planetary geology and new generation nuclear energy system design. The [Formula: see text]Ta([Formula: see text]) cross section had been measured between 1 eV and 800 keV at the back-streaming white neutron facility (Back-n) of China spallation neutron source(CSNS) using the time-of-flight (TOF) technique and [Formula: see text] liquid scintillator detectors. The experimental results are compared with the data of several evaluated libraries and previous experiments in the resolved and unresolved resonance region. Resonance parameters are extracted using the R-Matrix code SAMMY in the 1-700 eV region. The astrophysical Maxwell average cross section(MACS) from kT = 5 to 100 keV is calculated over a sufficiently wide range of neutron energies. For the characteristic thermal energy of an astrophysical site, at kT = 30keV the MACS value of [Formula: see text]Ta is 834 ± 75 mb, which shows an obvious discrepancy with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) recommended value 766 ± 15 mb. The new measurements strongly constrain the MACS of [Formula: see text]Ta([Formula: see text]) reaction in the stellar s-process temperatures.
ABSTRACT
Despite the widespread use of silica nanoparticles (SiO2 NPs) in biological and medical fields, their adverse effects have not been clearly elucidated. In this study, spherical SiO2 NPs with a 50 nm diameter were used to study their interaction with HaCaT cells. SiO2 NPs were found to be readily internalized into HaCaT cells and localized in the cytoplasm, lysosomes and autophagosomes. Decreased cell viability and damaged cell membrane integrity showed the cytotoxicity of SiO2 NPs. Significant glutathione depletion and reactive oxygen species generation, which reduced the cellular antioxidant level, could be the major factor of cytotoxicity induced by SiO2 NPs.